2010 was 0.01 degrees Celsius hotter than the number two hottest year 2005 and 0.02 degrees Celsius hotter than the third hottest year, 1998.
Having combined the datasets of Met Office’s Hadley Centre/Climatic Research Unit (HadCRU), NOAA’s National Climatic Data Center (NCDC) and NASA’s Goddard Institute for Space Studies (GISS), the World Meteorological Organisation can today confidently confirm 2010 broke the temperature record.
The three hottest years show no statistically significant difference, the press release states.
It also reports Arctic sea-ice cover in 2010 reached its lowest December extent, something that has not escaped our regulars. In the release WMO Secretary-General Michel Jarraud also stresses ‘the ten warmest years on record [since 1854] have all occurred since 1998.’
According to the WMO the measured temperature rise is greatest in the Arctic, Asia and Africa.
Climatologists argue that NASA’s dataset is likely to be superior to the other temperatures records, because its grid has the best Earth surface interpolation. According to NASA 2005 and 2010 were significantly hotter than 1998, even though that year spiked above the trend line due to the strongest El Niño in decades. [In fact, purely reading the measurements and ignoring statistical margins, the year 2009 ranks third hottest and 2007 fourth - the NASA graph shows.]
El Niño and La Niña
The first half of 2010 also fell in an El Niño episode, but that quickly switched to the strongest La Niña in decades. During a La Niña phase cool [with respect to rapid warming at the Earth’s surface one could even say fossil] deep ocean water spreads out across much of the Pacific Ocean’s surface, temporarily, slightly cooling the atmosphere.
NOAA’s recently updated land surface record also confirms 2005 and 2010 were significantly hotter than 1998.
© Rolf Schuttenhelm | www.bitsofscience.org